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(11) | EP 0 417 731 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Tool joint & method of hardsurfacing same |
| (57) A method is provided for applying grooved bands of hardsurfacing on a tool joint
for earth boring drill pipe. The hardfacing of the tool joint has tungsten carbide
granules in an alloy steel matrix. The tool joint is rotated and an arc between an
electrode and the tool joint is provided to create a weld puddle. The electrode is
reciprocated parallel to the tool joint axis and the granules are fed into the weld
puddle with the puddle being applied to the grooved bands around the exterior of the
tool joint to a groove depth of from between about 0.75 inches to about 0.150 inches.
The feed of the granules into the weld puddle is discontinued and the weld puddle
is continued to be applied around the tool joint and in the grooved bands to provide
a protruding substantially tungsten carbide free hardfacing surface about the outer
diamter of the tool joint of from between about 0.050 inches to about 0.175 inches,
and the hardfacing surface is machined down to substantially the outer diameter of
the tool joint. A tool joint having the above characteristics also is provided. |